Modular rotor assembly

ABSTRACT

Portions of the drive system for a piece of rotating equipment are pre-assembled into a subassembly. The subassembly can be held together by a carrier that is fabricated to accept the components in a proper alignment so that the carrier can be installed as a unit. In the preferred embodiment the carrier becomes a gearbox housing component that is installed saving the need for individual component alignment. Using the modular approach. The modular approach allows an assembly having a single part number to apply to a given compressor unit and further allows standardization of air ends of compressors with specific impellers and inlets added to meet requirements of a specific application.

FIELD OF THE INVENTION

The field of this invention is modular pre-assembly of rotatingcomponents of industrial machinery and more specifically compressors.

BACKGROUND OF THE INVENTION

Typically, when an end user specifies a compression need from amanufacturer the manufacturer tries to provide a unit from an availableproduct line to meet the performance and price parameters given. Sincethe potential applications and the specific parameters given bydifferent users can vary, each unit can wind up being specifically builtfor a unique application. In the drive system, the final driven speedfor the unit can vary, for example. Typically, in the past variouscomponents of the drive system to be installed in a gear box have to beindividually assembled and aligned with significant precision to preventpremature wear and failure. The assembly in the gearbox includes innerbearings and outer housings, a driven pinion/shaft, oil seals, animpeller to go into the compressor housing with an gas seal around theshaft, associated bits and pieces of the oil lubrication system andshaft end cap and associated fittings.

Assembling these components for every unit is labor intensive andtherefore expensive. It requires stocking of many options for givencomponents that can be assembled together in only so many discrete ways.This requires greater costs for storage, proper inventory and, most ofall, in assembly costs for a given unit.

Another costly issue is the need to precision fabricate all thecomponents to facilitate the alignment procedure. The individual parttolerances can add up making the ultimate alignment more difficult. Afailure to properly control alignment can result in premature bearing,seal or gear set wear. Manually assembling and aligning each unit can bea significant portion of the total labor cost.

What is needed and provided by the present invention is a way torationalize the assembly process to reduce its cost and improve itoperating reliability. What is envisioned is a modular pre-assembly ofthe major components of the drive into a gearbox housing. In thepreferred embodiment a carrier is precision machined to accept suchcomponents in an aligned condition to each other for quick assembly intothe gearbox housing. Those skilled in the art will better understand theinvention from the description of the preferred embodiment and theclaims, which define the scope of the invention that appear below.

SUMMARY OF THE INVENTION

Portions of the drive system for a piece of rotating equipment arepre-assembled into a subassembly. The subassembly can be held togetherby a carrier that is fabricated to accept the components in a properalignment so that the carrier can be installed as a unit. In thepreferred embodiment the carrier becomes a gearbox housing componentthat is installed saving the need for individual component alignment.Using the modular approach. The modular approach allows an assemblyhaving a single part number to apply to a given compressor unit andfurther allows standardization of air ends of compressors with specificimpellers and inlets added to meet requirements of a specificapplication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the currently known way of assembling the components of thedrive that requires significant time to insure proper componentalignment; and

FIG. 2 shows the modular approach of the present invention where some ofthe drive components are pre-assembled into a carrier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 represents the know way to assemble the illustrated components.An inner bearing 10 and an outer housing 12 are mounted on a gearboxhousing (not shown). Generally, the gearbox housing is horizontallysplit and the mating halves have a semicircular cutout so that uponassembly, the bearings are respectively supported in the opposed gearboxhousing walls. A geared pinion shaft 14 extends through bearings 10 and11. An end cap 18 goes over the end of the shaft 14. Various pipingmanifolds 20, which need to be connected to each of the bearings 10 and11, are illustrated. An oil seal 21 and a gas seal 22 are mounted to thehousings 12 and 13 that extend over them. The compressor housing (notshown) can be integrally cast in halves to form the gearbox lower andupper housings so that the assembly is completed around the housings 12and 13 and seals 21 and 22. The impeller 24 is fitted to the end of thepinion 14 and secured with a nut 26, preferably through the open end ofthe scroll or housing (not shown). The stocking of these individualcomponents and the custom combination of them to meet the requirementsof a specific unit adds assembly and record keeping and storage costs.The bearings 10 and 11 must be aligned to the pinion 14 so as tomaintain alignment of the gear meshes in the gearbox (not shown).

FIG. 2 illustrates the present invention. A carrier 28 holds thebearings 10 and 11, seals 21 and 22, end cap 18 and pinion 14. Thecarrier 28 has an opening to allow a bull gear (not shown) have accessto mesh with the pinion 14. Oil passages 32 can be integrated into thecarrier 28 and single or multiple end connections 34 can be provided atthe end 36 of the carrier 28. A reconfigured end cap 18 is mounted atthe end 36 of the carrier 28. Oil seal 21 is now within the carrier 28while gas seal 22 is at end 38 of the carrier 28.

Those skilled in the art will appreciate that the components mounted tothe carrier 28 are already aligned just by virtue of assembly to it andthe precision with which the carrier 28 has been manufactured. Thecarrier 28 with the components mounted to it can be fitted to the lowerpart of the gearbox housing and scroll (not shown) until the air seal 22is in a proper location as determined by alignment of groove 40 with anopening in the scroll or gearbox housing for insertion of a retainingWoodruff key or equivalent through the scroll or gearbox housing andinto the groove 40. At that point the top of the gearbox housing andscroll can be mounted to complete the assembly shown in FIG. 2. Theimpeller 24 can be mounted to pinion 16 either before or after the tophalves of the gearbox housing and scroll are put on.

Those skilled in the art will appreciate that although the preferredembodiment illustrated is in the context of a centrifugal compressor,the illustrated pre-assembly technique can be used on a variety ofrotating equipment applications and is applicable regardless of the sizeof the components or the horsepower of the connected driver. Thepre-assembly technique can be applied to directly driven rotatingequipment that does not employ a gearbox and a pinion such as 14.Configuring the carrier 28 to include oil passages 32 further speeds upthe assembly process. The use of an alignment groove such as 40, whichcan take a variety of forms and does not need to extendcircumferentially, also insures that the cartridge is properlypositioned with respect to the gearbox and the impeller 24 in thesurrounding scroll (not shown). The use of the cartridge 28 assuresalignment of the components mounted to it and that is the big time saveron assembly. The assembly can be stocked as a single part number and bewarehoused pre-assembled. For a centrifugal compressor assembly, theassembled components in a cartridge 28 allow the air end of thecompressor to become a common assembly. In that sense the impeller 24and inlets (not shown) can be assembled locally to meet the requirementsof a specific installation. The high level of alignment that can beobtained with the use of the cartridge will enhance the reliability ofthe rotating equipment and will provide additional hours of running timewithout maintenance or costly repairs. The cartridge concept isapplicable on installations where there is a gearbox housing that servesas a base or in other applications where the base is a structure such aswhen the drive is direct from driver to the shaft.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction, may be made without departing from the spirit of theinvention.

1. A subassembly for rotating equipment comprising: a plurality ofbearings supporting a shaft; a carrier to accept said bearings and shaftin a manner that aligns said bearings and shaft, a base to support saidcarrier.
 2. The subassembly of claim 1, further comprising: a gearmounted to said shaft; said carrier comprising an opening to allowaccess to said gear.
 3. The subassembly of claim 1, further comprising:at least one oil passage in the wall of said carrier that extends to atleast one of said bearings.
 4. The subassembly of claim 1, furthercomprising: a rotating equipment housing supported by said base with anend of said shaft extending into said housing when mounted to said base.5. The subassembly of claim 4, further comprising: a securing mechanismto selectively retain said cartridge to said housing when said cartridgeis properly positioned with respect to said housing.
 6. The subassemblyof claim 5, further comprising: a groove in said cartridge that allowsinsertion of a locking key when said groove is aligned with an openingin said housing.
 7. The subassembly of claim 1, further comprising: endclosures on opposed ends of said carrier with said shaft extendingthrough at least one of said closures.
 8. The subassembly of claim 7,further comprising: a rotating equipment housing supported by said basewith an end of said shaft extending into said housing when saidcartridge is mounted to said base; said end closure with said shaftextending therethrough seals against said rotating equipment housing. 9.The subassembly of claim 4, further comprising: said rotating equipmenthousing comprises at least a portion of a scroll for a centrifugalcompressor; said base comprises at least a portion of a gearbox housingformed to accept said cartridge in the desired orientation with respectto said scroll.
 10. The subassembly of claim 9, further comprising: agas seal on said carrier and aligned to said shaft.
 11. The subassemblyof claim 10, further comprising: an oil seal aligned to said shaft andin said carrier mounted between said air seal and one of said bearings.12. The subassembly of claim 11, further comprising: a gear mounted tosaid shaft; said carrier comprising an opening to allow access to saidgear. at least one oil passage in the wall of said carrier that extendsto at least one of said bearings.
 13. The subassembly of claim 12,further comprising: a rotating equipment housing supported by said basewith an end of said shaft extending into said housing when mounted tosaid base. a securing mechanism to selectively retain said cartridge tosaid housing when said cartridge is properly positioned with respect tosaid housing. a groove in said cartridge that allows insertion of alocking key when said groove is aligned with an opening in said housing.14. A method of assembling a piece of rotating equipment, comprising:pre-aligning a shaft and bearings in a cartridge; assembling thecartridge to the rotating equipment housing.
 15. The method of claim 14,comprising: providing a gear on said shaft; mounting said cartridge to agearbox housing; providing access in said cartridge to said gear. 16.The method of claim 14, comprising: aligning at least one seal to saidshaft in said cartridge.
 17. The method of claim 14, comprising:providing at least one oil passage in the wall of said cartridge. 18.The method of claim 16, comprising: providing a split gearbox; providinga centrifugal compressor scroll with a lower portion of said gearboxhousing; mounting said cartridge to said lower portion of said gearboxhousing to engage said gear to a drive within said gearbox;
 19. Themethod of claim 18, comprising: selectively locking said cartridge tosaid scroll when said gear is engaged to said drive.
 20. The method ofclaim 19, comprising: providing a spaced oil seal for said gearbox and agas seal for said scroll on said cartridge.